Analytic chemical sampling equipment has been available for years, including equipment that performs automatic sampling of multiple vials that each contain chemical samplers. Such equipment of often referred to as an “autosampler,” and typically includes a movable head that has a syringe that can be lowered into one of the sample vials to extract some of the chemical sample contained within that vial. EST Analytical, Inc. has sold autosamplers under various trademark names, including the CENTURION and the COBRA autosampler.
EST Analytical, Inc. also has patented various types of chemical handling equipment, including samplers. A list of such patents is provided, below.
Referring now to FIG. 1, the main electrical and electronic components of an EST “Centurion” are depicted, generally designated by the reference numeral 10. This Centurion device has a main processor board designated by the reference numeral 20, an operating system board at reference numeral 30, a digital input/output board (I/O board) at reference numeral 50, a “PWM” board (produces pulse-width modulated current) at reference numeral 60, a first motion control board at 70 and a second motion control board at 80.
The main processor board 20 includes a microprocessor circuit 22, a memory circuit 24, an input/output interface circuit 26, and a number of conductive pathways at 28 that transfer input and output signals to external devices. The processing circuit 22 can be virtually any type of computer device, and typically would be a microprocessor or a microcontroller. The memory circuit 24 will contain random access memory (RAM) and typically would also include read only memory (ROM), usually including some that is programmable, such as EEPROM devices. The I/O interface 26 will be able to interface both analog and digital signals.
The operating system board 30 essentially is a personal computer on a single circuit board. It includes a microprocessor 32, system memory 34, and I/O interface circuitry at 36. Part of the I/O interface circuitry is for outputting a signal to a display monitor, which is depicted as a user monitor 40. This would be a display screen in which the user can diagrammatically see the system components. The I/O interface 36 also has signals going to a LAN (local area network) output circuit 38, which can be connected to the Internet at 42. In the EST Centurion unit, the LAN circuit is an Ethernet circuit. A multi-conductor flat cable 90 is used to connect the signals between the operating system board 30 and the main processor board 20.
The digital I/O board 50 also contains a processing circuit 52 and memory circuit 54, along with an input/output interface circuit 56. The digital I/O board 50 controls many valves and solenoids, grouped on FIG. 1 in the block designated by the reference numeral 58. These valves and solenoids are the devices that control the fluidic flow pathways throughout the autosampler device that makes up the heart of the EST Centurion 10. Another multi-conductor flat cable 92 is used to connect the signals between the digital I/O board 50 and the main processor board 20. The digital I/O board 50 also has an output to a “GC” device 44. A GC device is an acronym for a Gas Chromatograph, which is a standard analytical instrument used for chemical analyses.
The PWM board 60 includes a processing circuit 62, a memory circuit 64, and a I/O interface circuit 66. This board controls a number of heaters grouped on FIG. 1 in the block 68, and also has other analog signals, including analog input from a temperature sensor 69. The heaters are typically energized using pulse-width modulation control signals, which are essentially square waves having a varying duty cycle, as controlled by the PWM board 60. There is a multi-conductor flat cable 94 that carries the signals between the PWM board 60 and the main processor 20.
The two motion control boards 70 and 80 are essentially identical in form, each having a micro-processor circuit and memory circuit as well as an input/output interface circuit. On the first motion control board 70, the processing circuit is at 72, the memory circuit is 74, and the I/O interface is 76. These devices control three different stepper motors, grouped on FIG. 1 by the reference numeral 78. These separate motors control the three axes of movement of the head module that contains the syringe that does the actual sampling of the chemicals that are placed in vials. A multi-conductor flat cable 96 carries the signals between the first motion control board 70 and the main processor board 20. However, it should be noted that this flat cable must be shielded, because otherwise the electromagnetic interference (EMI) created by the power signals energizing the heater 68 and the various motors 78 and 88 in the Centurion system will induce noise into the control signal wires that are inside the flat cable 96. Without the shield, the Centurion system would never work properly in all probability, because the interference produced by the power signals would mask the actual low-voltage control signals that run between the microprocessors on the motion control boards and the main processor board.
The second motion control board 80 has a processing circuit 82, a memory circuit 84, and an I/O interface circuit 86. This device controls three other motors in the system, grouped on FIG. 1 under the reference numeral 88. In a standard Centurion unit sold by EST Analytics, there is a gripper motor, a syringe motor, and a “soil elevator” motor, used for sampling solid materials. There is a multi-conductor flat cable 98 that runs between the first and second boards 70 and 80. It should be noted that flat cable 98 could instead have been run directly back to the main processor board 20, but that would have been a longer run, and this cable is also subject to interference from the power alternating current (“pulsed”) signals that run throughout the Centurion unit. Therefore, flat cable 98 is also shielded, even though it has a shorter physical run. These shielded cables are an extra expense that is often found in industrial equipment and laboratory equipment, because power signals are also found in those same environments.
Referring now to FIG. 2, an entire EST Centurion unit 10 is depicted, and shows some of the main electrical components. Easily seen in this view are a power supply 5, the digital I/O board 50, the operating system board 30, and one of the motion control boards 80. The motors 78 and 88 are placed inside the head module, approximately located as indicated on the figure. The valves and solenoids 58 and heaters 68, as well as the temperature sensor 69, are all located inside a separate compartment along with the plumbing that runs between such valves, solenoids, and other devices in the Centurion unit, as indicated by the arrow on FIG. 2. The user monitor 40 is also illustrated, and sits above the overall enclosure.
Referring now to FIG. 3, a more close-view of the Centurion unit's electrical control compartment is illustrated. The main processor board 20 is mounted beneath the operating system board 30, and the first motion control board 70 is mounted beneath the second motion control board 80. The digital I/O board 50 is mounted by itself, and the PWM board 60 is mounted off to the side, as shown. The shielded flat cables 96 and 98, are illustrated in this view. It should be noted that there are other flat cables in this EST Centurion unit, but they are not illustrated for purposes of clarity. In addition, there are dozens of other single conductor cables that run throughout the unit, mainly carrying power signals, or other types of control signals that are not grouped together in flat cables. These additional cables are also not illustrated, for purposes of clarity.
The two shielded flat cables 96 and 98 that are illustrated on FIG. 3 carry control signals, but they also run to the two motion control boards 70 and 80 which output power signals to the stepper motors 78, 88. Each stepper motor can draw up to two amperes maximum, and as noted above, the stepper motor signals are essentially a series of square waves, so they generate quite a large amount of EMI as they make the transitions from zero volts to full voltage. In addition, the heating elements in the heater 68 can draw up to three amperes per heating element, and those signals are also pulse-width modulated signals that generate a large amount of EMI. Simple stated, the autosampler device is a very noisy device when it comes to electromagnetic interference. When designing such equipment, particular attention must be devoted to protecting the control signals from that EMI noise, and in the case of the flat cables 96 and 98, shielding was needed. In essence, those two flat cables are the weakest link with regard to EMI noise tolerance.
The EST Centurion device 10 is designed for some expansion capability, in which a third motion control board can be mounted above the second motion control board 80. In that way additional stepper motors can be controlled, if a particular customer wants additional capabilities beyond the six stepper motors that are listed on FIG. 1. As would be expected, another shielded flat cable would be needed to run to that third motion control board, since that third board will induce yet more electrical noise into the Centurion environment. In that situation, the control signals for the third motion control board would run from the processor board 20, through the flat cable 96, through the first motion control board 70, through the second shielded flat cable 98, through the second motion control board 80, and then through a third shielded flat cable (not shown on FIG. 3), and finally to the third motion control board (also not shown on FIG. 3). While the capability for expansion exists in the Centurion unit, it becomes a rather complicated affair from a physical hardware and mounting of components standpoint.
It should be noted here that EST Analytics also sells a smaller version of an autosampler under the trademark name “COBRA.” The Cobra system has a motherboard and uses a multi-conductor flat cable to run signals to a motion control board. This device is a relatively low-power device, and has motors that only draw one ampere maximum per stepper motor. The motor pulse signals are also run in the same multi-conductor flat cable as the other control signals, so the system is fairly well maxed out with respect to any type of future expansion capability. Any higher amperage in the motor drive signals and there would be too much crosstalk between the flat cable conductors, and the control signals would be swamped by EMI. Another limitation at this time in the Cobra system is that only one of the three axes stepper motors is run at a time, mainly to eliminate additional crosstalk between the conductors. In addition, the system is not expandable, and it does not power any heaters. The Cobra system is rather limited as compared to the Centurion system.
The Centurion system can run multiple axes motors simultaneously, and as noted above, it can be expanded to have a third motion control circuit board. It also is a higher power device, drawing up to two amperes per stepper motor, and it can have heaters.